[Untracked] Fix feesPerGas null check & bump up default gas fee multiplier

[Drewmo123]

Summary

When testing ARB-SEPOLIA there were errors running a token-transfer since there were errors getting the gas fee. After looking closer, one of the values being returned maxPriorityFeePerGas was 0. On the next line we did a null check, but based on on JavaScript handles falsly values it treated 0 as false 🙃

So I updated the comparison to explicitly check for null or undefined. I also adjusted the calculations we did with adjustedMaxPriorityFeePerGas so we'd also scale up the value we got from alchemy. Without scaling this up the gas was too low to get accepted, kept getting replacement underpriced responses.

Also bumped up default gas fee to 1.2 multiplier. If at 1 most of the time there are problems sending out a transaction.

Detail

Testing

Documentation

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Requested Reviewers: @mention